Currently, illuminators are widely employed in devices such as portable computers, liquid crystal displays, cell phones, as well as traffic lights, spot lights, and other devices.
Referring to FIG. 5 and FIG. 6, a typical illuminator 10 includes a light-emitting chip 13, a first electrode 11, a second electrode 12, and a transparent shell 14.
The first electrode 11 includes a concave depression 15 defined in a top surface thereof. The concave 15 includes a bottom surface 17 and a side surface 16. The bottom surface 17 has a round rim. The side surface 16 encircles the round rim of the bottom surface 17. The light-emitting chip 13 is disposed on the bottom surface 17. The side surface 16 can reflect light.
Referring also to FIG. 7, the light-emitting chip 13 includes a P-type layer 131, an N-type layer 132 thereunder, and a light-emitting layer 133 interposed therebetween. The P-type layer 131, the light-emitting layer 133, and the N-type layer 132 cooperatively constitute a P-N junction. The N-type layer 132 is electrically adhered to the bottom surface 17, thereby electrically connecting to the first electrode 11. The P-type layer 131 is electrically connected to the second electrode 12 via a wire. The light-emitting chip 13 is substantially cubic.
The first electrode 11 applies a first voltage to the N-type layer 132, and the second electrode 12 applies a second voltage to the P-type layer 131. Light is emitted from the light-emitting layer 133 of light-emitting chip 13, and schematic light paths are shown in FIG. 6. Accordingly, the light can only be emitted from the side surfaces of the light-emitting layer 133 not covered by the P-type layer 131 and the N-type layer 132.
Because the light-emitting layer 133 emits light only from sides thereof, area of illumination is restricted and limited, thus intensity of the light-emitting chip 13 of the illuminator 10 is low.
What is needed, therefore, is an illuminator that can overcome the limitations described.